Patent GB-228827-A (GB)
Title: Improvements in or relating to duplex telegraphy
IPC: H04L5/22
Filed: 1923-08-02
Abstract: 228,827. Western Electric Co., Ltd., (Western Electric Co., Inc.). Aug. 2, 1923. Duplex telegraphs; distributor systems; typeprinting telegraphs.-Rapid duplex signalling over a continuously-loaded cable is effected by the provision of synchronously-operating switches, one at each station for alternately connecting the transmitters simultaneously and the receivers simultaneously to line. The duration of each such connection may be made equal to the line time, or the transmitter and receiver at each station may be alternately connected to line each more than once during a period equal to the line time. In one arrangement, Fig. 4, switches Y, carried by shafts adjusted to isochronism and correct phase relation, alternately connect the transmitters T and the receivers R to line during a half-revolution of each shaft, and the line time is brought to equality with this period of connection by adjustment of lengthening networks L. The shafts carry devices G, G<1> for arresting the motion of the tapes and associated mechanism of the transmitters and receivers when the corresponding apparatus is disconnected from the line. Alternatively, a duplex bridge arrangement may be used. In another arrangement, Fig. 7, with two transmitters and two receivers at each station, the switches are in the form of distributors adapted to subdivide the period of connection of each transmitter and of each receiver for the purpose of type-printing. Each distributor carries a ring of segments 1 - - 20, segments 1 - - 5, 6 - - 10, 11 - - 15, and 16 - -20 being connected respectively with transmitter 41, transmitter 42, printer 43, and printer 44, and a brush 45 connects successively segments 1 - - 10 and 11 - - 20 with segments T, R respectively on a second ring. The segment T is connected through a condenser K to a segment V, and the segment R is connected to the armature 47 of a receiving relay 49 connected through a shaping network 50 to a segment S. The segments V, S form a third ring, which is connected by a brush 51 to a continuous ring X joined directly to the line C. Another continuous ring L is connected by a brush 52 to a ring provided with four conducting segments 60 - - 63, segments 60 and 63 being connected respectively to printing magnets 54 and 57, and segments 61, 62 respectively to stepping-magnets 55, 56 of the transmitters. Fig. 8 shows an arrangement in which each transmitter and each receiver is connected to line more than once during a period equal to the line time. Each distributor carries transmitting segments 1 - - 10 connected successively by a brush 75 to a continuous ring T, receiving segments 18 - - 20 and 11 - - 17 connected successively by a brush 90 to a continuous ring R, switching segments 80 - - 89 and 100 - - 109 connected by a brush 112 to a continuous ring S, and control segments 115 - - 118 connected by a brush 123 to a continuous ring L, the brushes being carried by the same rotatable arm 76. The segments 1 - - 5, 6 - - 10, 11 - - 15, and 16 - - 20 are connected respectively to transmitter 71, transmitter 72, printer 73, and printer 74. The brushes 75, 90 travel over four transmitting and four receiving segments during the line time, which may be regulated for this purpose by adjustment of a lengthening network 113, and the brush 90 is therefore arranged to pass over the segment 18 in the interval between the passage of the brush 75 over the segments 1 and 2, the segments 19, 20, 11 - - 17 being correspondingly arranged in relation to the other transmitting segments. The segments 80 - - 89 connect the ring T to line C through a relay 77 and a condenser 78 as the transmitting segments are traversed by the brush 75, and the segments 100 - - 109 connect the line to a relay '91 with a shaping network 93 as the receiving segments are traversed by the brush 90. the armature of relay 91 connecting the ring R to battery 92. The segments 115 - - 118 connect battery 114 through brush 123 to tape-advancing magnet 119, printing magnet 120, tape-advancing magnet 121, and printing magnet 122 respectively. Curbing at transmitter.-A segment 110 is placed between each segment 80 - - 89 and the next succeeding segment 100 - - 109 and is connected through a condenser 111 and the armature of relay 77 to a battery for sending to line a short curbing impulse opposite in polarity to the signal impulse just transmitted.